Metals chelated by organic ligands are used as an important trace mineral source for humans and animals. Certain metal ions are especially known to be beneficial in stimulating plant growth leading to the production of larger, healthier plants, and increased production of fruits or vegetables. It has become generally accepted that the chelated forms of metals using organic acids are better assimilated by plants, animals, and human beings than are metal salts. Plant, animal and human tissue samples indicate increased metal content when exposed to metal organic acid chelates.
Metal chelates have been produced in the prior art from the reaction of a metal ion (usually in the form of soluble metal salt) with an organic acid or its salt having a mole ratio of one mole of metal to one to three moles of organic acid (depending upon the valency and coordination number of the metal ion) to form coordinate covalent bonds.
Amino and other organic acid chelates can be produced by reacting an organic acid with a metal ion in the form of an oxide, hydroxide or salt. In the prior art, for example, amino acid chelates have generally been made by reacting a metal salt with one or more amino acids, dipeptide, and polypeptide or protein hydrolisate ligands under appropriate conditions to form an amino acid chelate. Metal picolinates can be synthesized by the reaction of a metal salt with picolinic acid salt in an aqueous solution. Calcium or magnesium citrates can be synthesized by the reaction of citric acid with calcium or magnesium oxide, with either an hydroxide or carbonate water suspension. Other carboxylic acids such as hydroxy citric, malic, ascorbic, gluconic, etc. may be used for the preparation of metal salts, complexes and chelates.
A common example is the metal chelate FeEDTA which is produced by reacting the metal salt iron sulfate with an organic acid, ethylenediaminotetraacetic acid (EDTA), or its di or tetra sodium salts.
Patents indicative of the prior art are: U.S. Pat. No. 4,315,927 issued to Evans; U.S. Pat. No. 4,814,177 issued to Waldorf; U.S. Pat. No. 4,830,716 and U.S. Pat. No. 4,599,152 issued to Ashmead; U.S. Pat. No. 5,504,055 issued to Hsu; and U.S. Pat. No. 5,516,925 issued to Pedersen.
Although metal chelates formed by the reaction of free metal ions and chelating agents such as amino acids or EDTA are relatively inexpensive to produce, the one significant drawback to metal chelates formed by this process is that the metal chelate typically hydrolyzes at a pH≦11. Therefore, these metal chelates are not stable in strong alkaline environments.
The prior art has also identified what is termed a Maillard Reaction (MR). The MR occurs nonenzymatically in foods between reducing sugars and available amino groups during thermal processing. (“Reaction Conditions Influence the Elementary Composition and Metal Chelating Affinity of Nondialyzable Model Maillard Reaction Products”, Wijewickreme, Kitts, Durance; J. Agric. Food Chem., 1997, 45, 4577–4583).
The MR is an important reaction that occurs in food preparation. The reaction can occur under severe or mild heating conditions and through many complex chemical intermediates, which ultimately lead to the production of brown compounds, known as melanoidins. Melanoidins are known to be non-water soluble.
The formation of MR products (MRPs) is greatly influenced by both the reaction conditions and the sources of the reaction sugars and amino acids. The MR has been extensively studied from various chemical, technological, physical, and toxicological points of view in foods and medicines. Studies have reported that MRPs exhibit antioxidant activity and antimutagenicity (“Mutagenicity of Heated Sugar-Casein Systems: Effect of the Maillard Reaction”, Brands, C. M. J., Alink, G. M., Van Boekel, A. J. S., Jongen, W. M. F.; J. Agric. Food Chem. 2000, 48, 2271–2275).
It is important to note that MR is a sequence of natural chemical transformations occurring during food preparation. This reaction leads to the formation of compounds that, because their volatility, influence a food's overall flavor and taste.
The chemistry of the MR is known as a complex series of reactions leading to the formation of a variety of products, including the flavors, aromas and colors considered important in food science today. Despite the very complicated character of the MR, the first step of the interaction between reducing carbohydrates and amino compounds is the reaction of the carbonyl group of a carbohydrate molecule with the amino group of an amino compound. This reaction causes the formation of the first stable molecular product that has in its molecule both amino and carboxyl groups (“Food browning and Its Prevention: An Overview”, M. Friedman, J. Agric. Food Chem. 1996, 44, No.3, 631–653).
The main groups of products formed in the course of MR are N-substituted aldosamines, Shiff bases, aldosylamines, ketosamines, diketosamines, deoxysuloses, melanoidins, etc. The chemistry of these compounds is not well known and their formation mechanism remains obscure. In general, a given reaction mixture is a complicated composition of different organic compounds with unknown structures. However, because the starting materials are primarily: a) reducing sugars (i.e., poly hydroxy compounds containing carbonyl groups); and, b) amino groups containing compounds, the final products contain multiple oxygen and nitrogen atoms. As it is known to those skilled in the art, the strongest chelating agents are usually organic ligands having several functional groups in the molecules of oxygen and nitrogen atoms.
For thousands of years the only source of minerals for humans was cooked food. Vitally important minerals such as Zn, Ca, Mg, Mn, Cu, Fe and others were supplied to the bodies of our ancestors not in the form of metal glycinates, nicotinates, lisinates, etc., but from the cooking process utilized in preparing foods.